Transformer Analysis: Comparing Measured and Analytical Values

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Discussion Overview

The discussion revolves around comparing analytical values of a single-phase transformer with measured values obtained from various tests. The focus includes understanding the parameters involved in transformer analysis, such as core resistance and reactance, as well as calculating efficiency and power output based on load conditions.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant expresses uncertainty about how to compare analytical and measured values for a transformer, providing specific test results and asking for guidance on calculating efficiency and power output.
  • Another participant questions the definitions and measurement methods of "Rcore," "Xcore," and "eq" parameters, seeking clarification on the data presented.
  • A suggestion is made to compare results from the load test with those from open and short circuit tests, implying the use of an equivalent circuit model.
  • Further clarification is requested regarding the necessary measurements for a complete analysis, including primary and secondary resistances and inductances.
  • One participant proposes that the intent may involve performing unexcited measurements and assuming a fully coupled transformer to compare calculated and measured output voltages, though this is stated as a guess.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the definitions of certain parameters or the specific methodology for analysis. Multiple viewpoints and suggestions are presented, indicating ongoing uncertainty and exploration of the topic.

Contextual Notes

Limitations include potential missing assumptions regarding measurement techniques and the definitions of parameters used in transformer analysis. The discussion does not resolve how to calculate efficiency or power output definitively.

greg997
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I am asked to compare analytical values of the loaded transformer with measeured values of the transformer. I have got no clue how to do that. The transformer is singl ephase 230/115V with rated secondary current 0.43 A.
According to open circuit test the Rcore = 15.9kOhm, Xcore = 10.5kOhm. From SC test Req= 80 Ohm,
Xeq = 33.8 Ohm, Zeq = 86.8 Ohm

I have values of load test as follows. The load is connected to secondary R= 150k Ohm,
Vp = 211V, Ip= 24 mA, Pp = 3.2W, Vs = 115.1, Is=0.75 mA.

I am not sure what to do with that data. I also don't know how to find actual efficiency of the transformer. What is the power output of that transformer?
Thank you
 
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What exactly is "Rcore" and "Xcore"? Also your "ewq" parameters. How exactly were they measured?

What you should have measured id
 
greg997 said:
I am asked to compare analytical values of the loaded transformer with measeured values of the transformer. I have got no clue how to do that. The transformer is singl ephase 230/115V with rated secondary current 0.43 A.
According to open circuit test the Rcore = 15.9kOhm, Xcore = 10.5kOhm. From SC test Req= 80 Ohm,
Xeq = 33.8 Ohm, Zeq = 86.8 Ohm

I have values of load test as follows. The load is connected to secondary R= 150k Ohm,
Vp = 211V, Ip= 24 mA, Pp = 3.2W, Vs = 115.1, Is=0.75 mA.

I am not sure what to do with that data. I also don't know how to find actual efficiency of the transformer. What is the power output of that transformer?
Thank you

have you been introduced to an equivalent circuit model? I would guess that you have to compare your results from the 150k loaded experiment, to the results from the open and short circuit experiments.
 
What exactly are "Rcore" and "Xcore"? Also your "eq" parameters. How exactly were they measured?

What you need is:

with no other connections to the transformer:
primary inductance L11
primary resistance R1
secondary inductance L22
secondary resistance R2

with primary excited:
secondary voltage, open-circuit secondary: V2(oc)
secondary voltage, loaded secondary: V2(150K)

You might also determine the reverse voltage gain, i.e. V1(oc) and V1(150K) with V2 excited, although that should be redundant.

EDITED:
Not sure what the intent here is. Looks like you are to do just the unexcited measurements (the first four) and then assume a fully coupled transformer (k = 1.0) and compare the caculated output voltage with the measured one. But I'm just guessing.
 
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